This invention relates to a muscle hook that is particularly useful in ocular surgery, primarily to hold an eye muscle during surgery that is being performed to correct a strabismus condition. Surgery to correct strabismus usually involves shortening or lengthening of one or more of the eye muscles. To do this surgery, the eye muscle must first be cut away from the schlera of the eyeball so that it can be reattached at a different location on the eyeball. The surgeon's object is to make the cut flush with the surface of the schlera. In preparation for this cut, the primary function of the ocular muscle hook is to lift the muscle away from the eyeball to expose the end of the muscle at its place of attachment to the eyeball.
A major problem with muscle hooks of the prior art is that their design requires the hand of the surgeon (or of an assistant) that is holding the muscle hook to be positioned in interference with or obstruction of the surgeon's view of the operating area. The configuration of the present ocular muscle hook is such that, while the hook is in the actual application of holding an eye muscle, the hand holding the muscle hook is positioned laterally away from the surgeon's direct visual line to the operating area.
As a preliminary to the cutting of an eye muscle, the muscle must be identified. The muscle hook of the present invention has a tip on its leading end. The tip is shaped like a bulbous disk with all surfaces and edges rounded. The tip can be used as a probe to locate and identify the muscle to be cut and in so doing, the rounded surfaces and edges avoid cutting or tearing of the schlera. Also, once the muscle has been identified, to lift it, the muscle hook must be pushed beneath the eye muscle between the muscle and the schlera. In this procedure, the tip acts somewhat as a plow leading the way. Because of the width of the tip and because of its rounded faces and edges, tearing of the schlera is avoided as this plowing takes place.
Another problem with muscle hooks of the prior art is that they are awkward to hold and to manipulate. The muscle hook of this invention has a cylindrical handle of size, shape and weight similar to those of a mechanical pencil. The muscle hook is comfortable to hold and easy to manipulate. The cylindrical handle can be held within the thumb and first and second fingers of a hand, can be easily rotated, and can be tilted. The length of the handle is such that its upper end can rest against the body of the hand to provide stability during use of the muscle hook.
In use the muscle hook must be carefully and precisely manipulated as it is moved through the various angular paths. Initially, the thumb and fingers may simultaneously tilt and rotate the handle as the tip of muscle hook probes to identify the eye muscle to be lifted. Next a pivoting and shoving hand motion will be required to cause the tip to plow between the eye muscle and schlera. Once the tip has cleared the other side of the eye muscle, the muscle hook will be pivoted to align the leg of the muscle hook and under the eye muscle. Finally, the muscle hook will be lifted to raise the eye muscle from the eyeball. These various complex maneuvering motions are greatly facilitated by the shape of the handle combined with the angular relationship between the handle leg and tip of this muscle hook.
Another feature of this invention is the provision of a family of surgical instruments, of which this muscle hook is one, such that the size and shape of the handle and the overall weight of the muscle hook are all similar to those of other surgical instruments of the family. Thus, each instrument feels and handles much the same as the others and all are comfortable and familiar-feeling to the surgeon.
An important object of this invention is to provide an ocular muscle hook having a handle and a muscle holding leg projecting angularly from the handle to position a hand holding the handle away from the surgeon's line of vision when the leg is raising an eye muscle. Another object is to provide such a muscle hook with a tip angled upwardly from the leg to prevent the muscle from sliding off the leg.
A further object of this invention is to provide an ocular muscle hook that has a cylindrical handle combined with a configuration of handle, leg and tip to allow precise maneuverability of the muscle hook, to probe for the proper muscle, plow between that muscle and the schlera, and raise the muscle.
Other objects and advantages of the invention will be apparent from the description which follows.